A new species of hydrocoral, Millepora boschmai, is described from the Gulf of Chiriqui, Pacific Panamá. This species was first found in the early 1970's, but it has disappeared from this area as a result of the severe 1982-83 El Nino-Southern Oscillation (ENSO) event. Because the species has never been encountered outside the Gulf of Chiriquí, it is assumed that it was endemic to this area and that its disappearance marks an extinction event, representing the first documented case of a modern extinction of a tropical marine organism due to natural causes.